Close enough to Napa to check it out...believe it or not, wine country is also kid friendly.
Marine World in Vallejo is also in fairly close proxemity (it's an amusement park, not a USMC spa), plus San Francisco is less than an hour away, and Silicon Valley has Paramount's Great America.
The whole Bay Area is lots of fun...I hope you and your family have a great trip here - just stay away from the brown acid!
ADG